The invention relates to a pull-out guide assembly for drawers comprising a pull-out rail fastened to the drawer, a supporting rail fastened to the body of the piece of furniture and a center rail differentially running between said two rails on each side of the drawer, running carriages holding load-transmitting cylindrical bodies being arranged between said rails, and driving rollers running on the supporting rails and on the pull-out rails being mounted on the center rails.
A pull-out guide assembly of the afore-mentioned kind allows substantially full extraction of the drawer from the body of the piece of furniture and hence guarantees optimal access to the contents of the drawer.
An example of such a drawer is described in U.S. Pat. No. 3,901,564. Steel balls which are held in cages are used as cylindrical bodies in the pull-out guide assembly described in the cited Patent. These steel balls require relatively complicated profiles the supporting rails and of the pull-out rails. Furthermore, no run-in means for the drawer is provided because of the rail profiles.
To be able to use simpler rail profiles in connection with the same loading capacity, ball bearings would have to be used instead of steel balls according to the known state of the art. Ball bearings cause, however, a considerable increase of costs.